1. Field
Apparatuses and methods consistent with the exemplary embodiments relate to a wireless communication apparatus and a control method thereof, and more particularly to a wireless communication apparatus and a control method thereof, which can efficiently transmit data to a plurality of intragroup receivers desired to receive the same data.
2. Description of the Related Art
In a wireless infrastructure network using a wireless access point (AP), multicast transmission methods all perform wireless communication with respect to a wireless AP like a unicast transmission method. However, the multicast transmission method transmits data via not respective channels of 1:1 but the same channel of 1:n channels on the contrary to the unicast transmission method.
FIG. 1 is an example showing operations of a wireless communication apparatus in the related art. Referring to FIG. 1, the operations of the conventional wireless communication apparatus will be described.
A transmitter 3 transmits multimedia data to receivers 4 and 5 within a multicast group through wireless communication under an environment of a predetermined space. The transmitter 3 designates destination information as a multicast destination and transmits data to an wireless AP, i.e., a wireless communication apparatus 2 by a multicast method. The wireless communication apparatus 2 transmits the received multicast data to the receivers 4 and 5 within a predetermined space. Basically, in a broadcast transmission method, the multimedia data is transmitted toward the first receiver and the second receiver simultaneously. The receiver within a predetermined space determines whether destination information of data is multicast destination to which a user belongs, and then receives the data normally.
However, in institute of electrical and electronics engineers (IEEE) 802.11 Wi-Fi standards, acknowledgement (ACK, i.e., response to normal reception) is not used at the multicast transmission. This is to prevent repetitive generations of the ACK. However, such nonuse of the ACK brings the following problems.
First, data loss occurs when the receiver cannot receive the multicast data normally, thereby having low reliability.
Second, it is impossible to request the transmitter to do retransmission.
Third, when there is collision between wireless terminals due to simultaneous transmission, a collision avoiding method (IEEE 802.11 standards) is not normally performed since there is no feedback from the ACK.
Fourth, there is irrationality between a unicast transmitter and a multicast transmitter.
Fifth, the lowest modulation method has to be used for the transmission even though intragroup receivers are different in communication environments due to difference in a distance, a communication obstacle, etc., and it is therefore impossible to use a high modulation method for the transmission.